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Regulatory Assets and Liabilities (ROE of Tampa Electric) (Details) - Tampa Electric Division [Member] | 12 Months Ended
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Dec. 31, 2018
Florida Public Service Commission [Member] |
Public Utilities, General Disclosures [Line Items] |
Public Utilities, Approved Equity Capital Structure, Percentage | 54.00%
Minimum [Member] | Florida Public Service Commission [Member] |
Public Utilities, General Disclosures [Line Items] |
Public Utilities, Approved Return on Equity, Percentage | 9.25%
Maximum [Member] |
Public Utilities, General Disclosures [Line Items] |
Public Utilities, Approved Return on Equity, Percentage | 10.25%
Maximum [Member] | Florida Public Service Commission [Member] |
Public Utilities, General Disclosures [Line Items] |
Public Utilities, Approved Return on Equity, Percentage | 11.25%

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